In accordance with recent technological progress, development of semiconductor devices such as one-chip MMICs (Monolithic Microwave Integrated Circuits) operating in a milliwave band (e.g., 60 GHz or 76 GHz) have been advanced.
In such a milliwave band, since minute inductance or capacitance affects matching characteristics of the semiconductor device, wiring for connecting an MMIC and its package should be as small as possible. Therefore, not gold wire connection but flip-chip connection using gold bumps having an inductance smaller than that of wires has been proposed (see, for example, a semiconductor device disclosed in FIG. 1 of Patent Document 1).
In MMICs which operate in a high-frequency band (that includes the milliwave band), the surroundings of the MMIC are often subjected to electric shielding so as to block unnecessary electromagnetic waves emitted from the MMIC. Many shielding structures using the above-described flip-chip connection have been proposed.
For example, in a conventional technique for implementing a shielding structure disclosed in Patent Document 2, back and side surfaces of an MCM (Multichip Module) substrate which employs the flip-chip connection are metalized, and the metalized side surfaces are connected via solder to a packaging substrate on which a solder wall is formed.
Additionally, in a conventional technique for implementing a shielding structure disclosed in Patent Document 3, bumps connected to a ground electrode are arranged so as to surround a functional circuit, and a cover substrate is connected to the bumps.
In addition, a semiconductor device disclosed in Patent Document 4 has a semiconductor chip, a pair of ground pads provided on the semiconductor chip, and a pair of signal line pads provided between the ground pads on the semiconductor chip.
A first metal layer is provided on a side wall of the semiconductor chip. A second metal layer is connected to the first metal layer, and reaches the ground pads. To each of the signal line pads, one end of a bonding wire is connected. The other end of each bonding wire is connected to a signal line.
Furthermore, a third metal layer is provided on the lower surface of the semiconductor chip.